Generally, a condenser microphone which has been widely used in mobile equipment or audio equipment consists of a voltage bias element, a diaphragm and back plate pair for forming a capacitor which is changed corresponding to a sound pressure, and a JFET for buffering an output signal. This typical condenser microphone consists of an assembly which is integrally assembled by sequentially inserting a diaphragm, a spacer ring, an insulating ring, a back plate and a conductive ring into a case and then bending an end of the case toward a PCB side after inserting the PCB which is mounted with circuit parts.
Meanwhile, recently, a semiconductor fabricating technology using a micromachining technology has been introduced for an integrated micro device. According to this technology which is called MEMS (Micro Electro Mechanical System), a sensor, an actuator and an electro mechanical structure can be fabricated in a μm unit using a micromachining technology which applies a semiconductor fabricating process, especially, an integrated circuit technology. A MEMS chip microphone manufactured by the micromachining technology has merits that miniaturization, high-performance, multifunction and integration can be obtained through the high precise micromachining technology and safety and reliability can be enhanced.
However, since the MEMS chip microphone manufactured by the micromachining technology performs electrical driving and signal processing, it is required to package the microphone with another special purpose semiconductor chip device, that is, an ASIC (Application Specific Integrated Circuit).
A conventional technology for packaging a MEMS chip microphone is disclosed in U.S. Pat. No. 6,781,231 published Aug. 25, 2004 and entitled “Micro Electro Mechanical System Package with Environmental and Interference Shield”. The above package has a structure for adhering a cover which consists of an internal conductive layer and an external conductive layer on a multi-layered substrate which is alternately overlapped by a conductive layer and a non conductive layer using a conductive adhesive.
Thus, the conventional packaging method has problems in that a manufacturing cost is raised and a bonding property is deteriorated due to a complex process, and the method is sensitive to external noise such as an electromagnetic noise and the like since a non conductive material unlike a metal housing is used.